Ok so I feel horrible and the biggest idiot. I bought 6 red sexlinks several weeks ago and didn't think of checking for bugs. I have many other chickens and im very diliget in keeping my coop spotless. I clean it every single day and do a full scrub down once a month. Anyway I bought these sexlinks and ive had them for several weeks now and theyhave nit been laying. Long story short one hen I found dead yesterday. I was puzzled and thought she died of maybe old age as I found no trauma to her at all. I went out this evening because something just told me to check their vents for signs of old age as I thought id been dooped. Well I just about fell over when I saw lice crawling around the vent. Its 11:30 pm and I ran to wal mart and got sevin dust and just finished dusting all 20 of my chickens. What I need to know is do I need to get any medicineor vaccine? Do they have internal parasites due to the lice? Everyone looks and acts extremely healthy but im very worried about internal stuff caused by lice. If I need medicine what do I get? Btw I dusted every single part except the head and I sprinkled the coop floor and I plan on repeating again in a month.